The present invention relates to a system and a method for estimating electricity consumption of an electric appliance, which can estimate individual electricity consumption of a plurality of electric appliances used in a household (user of electricity), and an abnormality alarm system of an electric appliance utilizing the same. More particularly, the present invention relates to a system and a method for estimating electricity consumption of an electric appliance, which estimate individual electricity consumption of a plurality of electric appliances by a non-intrusive way, and an abnormality alarm system for electric appliances utilizing the same.
In the present specification, a term xe2x80x9cnon-intrusivexe2x80x9d means setting a measuring sensor at one position in the vicinity of an entrance of a feeder to a user and the state that the measuring sensor is not attached in accordance with each branch circuit on the downstream side of the feeder or it is not attached in accordance with each electric appliance connected to the circuit. Further, an inverter-driven appliance means an appliance which has an inverter mounted thereon and can continuously change the operation of the device from a low output to a high output. Electricity consumption of the inverter-driven appliance continuously varies from a small value to a large value in accordance with an output. Furthermore, a non-inverter appliance means an appliance which does not have an inverter mounted thereon and whose operation is simply limited to, e.g., On and Off. Electricity consumption of the non-inverter appliance takes a restricted value in accordance with on-off operation.
As a monitoring system which non-intrusively estimates the operating status of an electric appliance, EPRI (Electric Power Research Institute; US) has conventionally realized such an apparatus by using an algorithm developed in MIT (Massachusetts Institute of Technology; US). This monitoring system takes on-off operation of an electric appliance as temporal stepwise changes in a total load demand curve of a household, specifies an electric appliance which has been turned on or off, and estimates its operating status based on a rated electricity consumption and a rated power factor of the electric appliance. Therefore, an electric appliance which is simply turned on or off can be specified, and its operating status can be estimated.
In recent years, however, inverter-driven appliances such as an air conditioner have spread in general households, and it is often the case that both non-inverter and inverter-driven appliances are used in the same environment. Since the inverter-driven appliance controls an output in accordance with the load status, electricity consumption also varies in accordance with this control. Therefore, temporal transition of electricity consumption does not necessarily fluctuate in the step form, but it may fluctuate slowly or irregularly.
Thus, under the circumstance that the inverter-driven and the non-inverter appliances are both used, it is difficult not only to estimate individual electricity consumption of each electric appliance but also to estimate the operating status of the electric appliance by using the conventional monitoring system developed by EPRI mentioned above.
It is an object of the present invention to provide a system and a method for estimating electricity consumption of an electric appliance, which can non-intrusively estimate individual electricity consumption of a plurality of electric appliances used in a household under the circumstance that non-inverter and inverter-driven appliances or the like are both used. Moreover, it is another object of the present invention to provide a system which warns a malfunction arising in electric appliances used in a household.
To achieve this aim, the present inventor has paid attention to a pattern of harmonic currents generated by an electric appliance set in a household, and considered obtaining fundamental and higher harmonics of total load current and their phase differences from voltage based on total load current and voltage measured in the vicinity of a service entrance, thereby estimating electric appliances used in the household and their individual electricity consumptions. For example, they considered such estimation by applying a pattern recognition technique using an estimation algorithm such as a large margin classifier or a neural network.
It is well known that an electric appliance which has an inverter circuit and rectifiers therein generates harmonics inherent thereto. In addition, other than a simple resistance circuit, even though electric appliances have any circuit other than an inverter circuit and an rectifier circuit therein, most of such appliances generate harmonics inherent thereto. If the operating status of the electric appliances is the same, the electric appliances generate the same harmonics. Thus, the present inventor has conceived that, if the harmonics intruding to the user from the outside is the same, the operating status of electric appliances in the household can be estimated by checking fundamental and higher harmonics of total load current and their phase differences from voltage in the household.
According to the present invention, in view of the above-described conception, there is provided a method for estimating individual electricity consumption of a plurality of electric appliances used in a household, wherein there is previously created a model which estimates individual electricity consumption of electric appliances from the relationship between data concerning fundamental and higher harmonics of total load current and their phase differences from voltage based on total load current and voltage obtained from combinations of various use states of a plurality of the electric appliances and corresponding individual electricity consumptions of a plurality of electric appliances in service, and individual electricity consumption of electric appliances in operation is estimated by using the model with data concerning fundamental and higher harmonics of total load current and their phase differences from voltage based on total load current and voltage detected in the vicinity of a service entrance of a user. Additionally, according to the present, invention, there is provided a system which estimates individual electricity consumption of a plurality of electric appliances used in a household, the system comprising: a measuring sensor set in the vicinity of a service entrance to the user; data extracting means for fetching data concerning fundamental and higher harmonics of total load current and their phase differences from voltage based on total load current and voltage detected by the measuring sensor; and estimating means for estimating individual electricity consumption of electric appliances in service by previously creating a model which estimates individual electricity consumption of electric appliances from the relationship between data concerning fundamental and higher harmonics of total load current and their phase differences from voltage based on total load current and voltage obtained from combinations of various use states of a plurality of the electric appliances and corresponding electricity consumptions of the electric appliances in operation and receiving fundamental and higher harmonics of total load current and the phase differences from voltage as inputs.
In this case, when data concerning fundamental and higher harmonics of total load current and their phase differences from voltage in a household is obtained, it is possible to estimate individual electricity consumption of a plurality of electric appliances used in the household by utilizing a model which is previously configured to associate typical electric appliances"" fundamental and higher harmonic currents and their phase differences from voltage or those acquired when arbitrarily combining and operating such electric appliances with corresponding individual electricity consumptions in service.
According to the present invention, only setting the measuring sensor in the vicinity of the outdoor service entrance can suffice, and the measuring sensor does not have to be set in accordance with each electric appliance to be measured. Therefore, there can be obtained an advantage of less degrees of violation of privacy or less additional wirings or the like when setting the present system to the household.
Further, in the system for estimating electricity consumption of an electric appliance according to the present invention, it is preferable that the estimating means generates a model which estimates an approximate electricity consumption curve, i.e., individual electricity consumptions of electric appliances by providing an estimation algorithm with a training set consisting of data concerning fundamental and higher harmonics of total load current and their phase differences from voltage based on total load current and voltage obtained from combinations of various use states of a plurality of electric appliances and combinations of individual electricity consumption in various operating status of these electric appliances and corresponding individual electricity consumptions of the electric appliances, which are solutions for the combinations, and performing learning on parameters of the electricity consumption curve.
As the training set in this case, some are selected from pairs of typical electric appliances or arbitrary combinations of such electric appliances and arbitrary combinations of the operating status with respect to them and individual electricity consumption of the electric appliances, which are solutions relative to such combinations. Then, by giving the training set to the estimation algorithm and causing it to learn in advance, the estimating means is set available. That is, the data concerning fundamental and higher harmonics of load current and their phase differences from voltage and corresponding electricity consumption of a plurality of electric appliances in service, which are obtained by operating typical electric appliances or arbitrarily combining and operating these electric appliances, are given as the training set to the estimation algorithm to have it learn in advance and make a model which estimates electricity consumption of individual electric appliances from the relationship between harmonics pattern and corresponding electricity consumption of a plurality of electric appliances in service obtained from combinations of various use states of a plurality of the electric appliances. As a result, it is possible to estimate electricity consumption of each electric appliance which is in service by using the model which can estimate electricity consumption of each electric appliance through the estimation algorithm even if unknown measurement data are inputted. Thus, when the data concerning fundamental and higher harmonics of total load current and their phase differences from voltage obtained by the measuring sensor provided in the vicinity of the service entrance to the user is actually fetched and given to the estimating means which is available after completion of learning as mentioned above, the estimating means can estimate individual electricity consumption of the electric appliances which are in service.
Therefore, individual electricity consumption of a plurality of the electric appliances used in the household can be estimated by the estimating means with data concerning fundamental and higher harmonics of total load current and their phase differences from voltage obtained from the data extracting means through the measuring sensor.
Here, as the estimating means, it is preferable to use an estimation algorithm of a large margin classifier or an estimation algorithm of a neural network. In particular, use of the large margin classifier can further improve the estimation accuracy with respect to combinations of the electric appliances including non-inverter appliances.
Furthermore, the above-described system for estimating electricity consumption of an electric appliance can be utilized for an abnormality alarm system which warns about malfunction of an electric appliance. This abnormality alarm system determines presence/absence of malfunction of an electric appliance or an electric system based on their individual electricity consumption obtained by the above-described system for estimating electricity consumption of an electric appliance. In this case, information about malfunction of an electrical appliance which may lead to a fire disaster, safety of residents in the household which can be detected from how a specific electric appliance is used, safety in the household or the like can be determined by the non-intrusive method and can be transmitted to the outside.